The objectives of this program project are: 1. To maintain and develop an analytic ultracentrifuge facility and to utilize it where the most refined ultracentrifugal analyses are required; 2. To develop analytic and preparative techniques for the isolation and characterization of each major lipoprotein class and its subfractions; 3. To develop, evaluate and calibrate simplified methods for lipoprotein analysis; 4. To utilize electron microscopy in conjunction with other physical and chemical measurements for the fine structure study and functional interrelationships between lipoprotein fractions and lipoprotein metabolism; 5. To study the effects of steroid hormones on lipoprotein synthesis and catabolism at the cellular level using rat hepatocyte cultures; 6. To elucidate the compositional, morphologic, and interactive determinants of naturally occurring lipoprotein distributions and specific lipoprotein distributions produced during in vitro transformation by enzymatic or physical-chemical means; 7. To delineate properties of degradation products from native lipoprotein distributions and relate them to normal and abnormal lipoprotein distributions; 8. To study the effect of gonadal hormones on serum lipoprotein distribution, particularly HDL; 9. To study the changes in substrate lipoproteins during lipolysis by purified hepatic and extrahepatic lipases; 10. To study the effects of ultracentrifugation. Physical and chemical characterization will include analytic ultracentrifugation, electron microscopy, various forms of electrophoresis and column chromatography, CHN elemental analysis, spectrometry and standard procedures for protein and lipid analysis.